I filled my car up at the local Mobil and then went through their power washer. When I arrived at home I noticed the gas cap was dangling. I'm not sure how much water may have gotten into the fuel tank. I've drove about 30 miles so far after the mishap and I don't notice anything different. Should I worry and should I do anything about the fact that there was water that entered my fuel tank?

You might want to buy a bottle of the gas drier that takes water out of your gas tank. Maybe only use 1/2 bottle.